The β-to-γ Transition in BiFeO3: A Powder Neutron Diffraction Study

Authors

  • Donna C. Arnold,

    1. School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST (UK)
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  • Kevin S. Knight,

    1. ISIS Facility, Rutherford Appleton Laboratory Chilton, Didcot, OX11 0QX (UK)
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  • Gustau Catalan,

    1. Department of Earth Sciences, University of Cambridge Downing Street, Cambridge, CB2 3EQ (UK)
    2. Present address: ICREA and CIN2 (CSIC-ICN), Campus Universitat Autonoma de Barcelona, Bellaterra 08193, Barcelona, Spain
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  • Simon A. T. Redfern,

    1. Department of Earth Sciences, University of Cambridge Downing Street, Cambridge, CB2 3EQ (UK)
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  • James F. Scott,

    1. Department of Earth Sciences, University of Cambridge Downing Street, Cambridge, CB2 3EQ (UK)
    2. Present address: Department of Physics, Cavendish Laboratory, University of Cambridge J. J. Thompson Avenue, Cambridge, CB3 0HE, United Kingdom
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  • Philip Lightfoot,

    1. School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST (UK)
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  • Finlay D. Morrison

    Corresponding author
    1. School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST (UK)
    • School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST (UK).
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Abstract

High-temperature powder neutron diffraction experiments are conducted around the reported β–γ phase transition (∼930 °C) in BiFeO3. The results demonstrate that while a small volume contraction is observed at the transition temperature, consistent with an insulator–metal transition, both the β- and γ-phase of BiFeO3 exhibit orthorhombic symmetry; i.e., no further increase of symmetry occurs during this transition. The γ-orthorhombic phase is observed to persist up to a temperature of approximately 950 °C before complete decomposition into Bi2Fe4O9 (and liquid Bi2O3), which subsequently begins to decompose at approximately 960 °C.

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